Understanding the structure and properties of geological formations often reduces the cost of drilling and production of oil and gas wells. Measurements are typically performed in a borehole (i.e., downhole measurements) in order to attain this understanding. To obtain such measurements, a variety of sensors and mounting configurations may be used.
For example, resistivity tools are widely used in oil field exploration applications for determining zones in a formation that may contain hydrocarbons. Accurate determination of the formation resistivity is useful in assessing the feasibility of production for a particular well. However, resistivity measured by the tool is often affected by factors other than the formation resistivity. For example, the presence of the borehole itself, as well as invasion zones, may change the measurement values. In addition, caving and rugosity can distort shallow resistivity measurements.